The present invention relates to a method and device for detecting ammonia odors and uses thereof, in particular for diagnosing helicobacter pylori urease infection.
It is estimated that almost 1 in 10 adults will develop a stomach ulcer at some time in their lives. The bacterium Helicobacter pylori (HP) is known to be the cause of most stomach ulcers and ulcers of the duodenum and, once detected, can be cured by treatment with antibiotics. H. pylori (HP) produces an active form of the urease enzyme, which hydrolyzes urea into ammonia and carbon dioxide. Since ammonia is the key component generated by urease-catalyzed hydrolysis of urea, it follows that the presence of this compound in a person's breath can be used to diagnose helicobacter pylori urease (HPU) infection.
However, there are not many systems to detect ammonia odors, and of those available, most require the use of expensive instrumentation and are complex in operation (and hence not suitable for use by untrained users).
In general, HPU infection is diagnosed by analyzing the difference of exhaled ammonia and/or CO2 levels from a patient before and after swallowing a dose of radioactive urea. The levels of ammonia in HPU infected persons are usually between 100 to 200 parts per million (ppm) after swallowing the urea, whereas the levels of ammonia in an uninfected person after having swallowed the urea are much the same as before taking the urea (<2 ppm).
The patient first drinks a solution of citric acid as a background test and two baseline expired breath samples are collected in Mylar breath collection balloons from Kimberly-Clark/Ballard Medical Devices of Draper, Utah. The patient then drinks a second solution containing citric acid and carbon-14 labeled urea, and another two expired breath samples are taken after 30 minutes. The samples of expired breath are then analyzed for carbon-14 labeled carbon dioxide. The test is considered positive for H. Pylori infection when the difference between the control breath and the labeled breath samples are greater than 3.5 parts per thousand. This test is both expensive and time consuming.
Therefore, there is a clear need for a simple, safe device which needs neither expensive instrument nor radioactive materials for detecting ammonia from HPU infection and other sources.